1. Field of the Invention
The present invention relates to a directional coupler used in a microwave band or the like.
2. Description of Related Art
A directional coupler is widely used in order to carry out monitoring of electric power. As a directional coupler, there is a directional coupler having a structure of broadside-coupling two lines (for example, refer to the following nonpatent reference 1). By broadside-coupling lines this way, a directional coupler can be implemented.